Sawyer to replace Gibson on 'World News'

After almost 35 years at ABC, Gibson is retiring from anchoring the evening news."It has not been an easy decision to make," said Gibson in a written statement. "This has been my professional home for almost 35 years. And I love this news department, and all who work in it, to the depths of my soul."

In 2006, Gibson was asked to step in the anchor seat for "World News" following Bob Woodruff's serious war injuries and Elizabeth Vargas's pregnancy. Gibson said it was an honor to do so, even though he had planned on retiring in 2007.

"For 19 years, my mornings have not just been good, they've been great. Thank you," said Gibson on his final day with "Good Morning America."

Gibson's anchor seat will be filled by his former GMA co-host, Diane Sawyer in January.

In a statement, ABC News President David Westin said: "Diane Sawyer is the right person to succeed Charlie and build on what he has accomplished. She has an outstanding and varied career in television journalism, beginning with her role as a state department correspondent and continuing at '60 Minutes,' 'Primetime Live' and Good 'Morning America.'"

Gibson says he would still like to occasionally contribute to ABC News and that he will be in discussions about what his future role might be.